Non-steroidal anti-inflammatory drugs influence cartilage healing

Retrograde intramedullary nailing is commonly performed to stabilize distal femoral shaft fractures which may lead to iatrogenic injuries of the knee articular cartilage. The limited regenerative capability of cartilage may further be hindered by intake of non-steroidal anti-inflammatory drugs (NSAIDs) which are usually advised for injuries of the musculoskeletal system. The current study was designed to evaluate the histological changes in the femoral articular cartilage of knee joint after retrograde femoral nailing of rats.

Retrograde intramedullary nailing was performed in 36 adult male Wistar rats, divided into three groups of 12 each. Groups 1 and 2 were given nonselective and selective COX 2 inhibitors, respectively, while the third group was taken as control. Half of the animals from each group were sacrificed at the second week, and remainder on the seventh week, and samples of the femoral articular cartilage were assessed for cartilage regeneration according to the modified Mankin scoring on histology while BMP-2 expression was evaluated on immunohistochemistry.

Mean modified Mankin scores for cartilage degradation were increased in animals taking NSAIDs at the second and seventh weeks of healing (P = 0.02, P < 0.001 respectively). There was a significant decrease in chondrocytes at the second week (P = 0.001), along with the loss of proteoglycan content in these animals at both time points (P = 0.001). The BMP-2 expression was significantly enhanced in the control group at the second (P = 0.001) and seventh weeks (P = 0.001).

The results reveal that intake of NSAIDs hinders the process of cartilage healing by reducing the number of chondrocytes and loss of proteoglycan content and decreased expression of BMP-2.